A typical hardwood, laminate, or engineered flooring system may include two or more layers. A top layer typically details the pattern and texture of the product, and may include a protective layer, such as a hard coating, for durability. A core layer may be prepared from pressed fiberboard, for example, or from other suitable materials. A bottom layer may be included to stabilize the product and to protect it from deleterious effects of moisture. Frequently, laminate or engineered flooring systems employ some type of tongue and groove design to allow the pieces of the flooring to bond together without requiring the use of adhesive.
It is well-known that moisture may cause undesirable cupping or warping of the flooring system. A vapor barrier may be employed to protect the laminate or engineered flooring system from damage caused by moisture. Though a vapor barrier may provide some protection against moisture damage, vapor barriers tend to increase the cost and installation complexity of such flooring systems.
Another issue that may be experienced with flooring systems is the sound that may be produced when the floor is used. In multi-story structures, for example, sound created by use of an upper unit floor may be transmitted down into the unit below. Likewise, sound may be reflected back into the unit in which it is created. A sound barrier layer may be employed to reduce one or both of transmitted and reflected noise. Typical sound barrier layers include dense rubber and plastic sheets, corks, recycled fibers, and various types of foams. Such sound barriers, however, tend to be heavy and to add to the complexity and overall cost of installation.
Examples of conventional foams used in flooring applications have EPC contents, densities, and gel fraction that, in combination, result in compressive strengths below about 0.50 kg/cm2. These properties of conventional olefin foam underlayments combine to produce relatively high reflected sound pressure levels (i.e., greater than about 13.5 dB average) in the 300 Hz to 1000 Hz range. Other underlayment materials, such as fiber pad, cork, and non-cross-linked foam, for example, also tend to produce relatively high reflected sound pressure levels in the 300 Hz to 1000 Hz frequency range. Such materials also tend to produce high moisture vapor transmission rates (MVTR) unless additional vapor barrier layers are incorporated.
Accordingly, it would be desirable if there were available flooring systems that produced relatively low sound reflection (e.g., less than about 13.5 dB average over a range of 300 to 1000 Hz) and moisture vapor transmission rates (e.g., less than about 3.0 lb/1000 ft2/24 hr) by ASTM F 1249 test method, without the cost and installation complexity conventional systems typically involve.